Fuel use rate meter for engines

ABSTRACT

A meter capable of accurately measuring volume or weight of fuel consumed by an engine per unit time. The meter includes a piston driven in reciprocating movement by fluid being pumped therethrough by the engine fuel pump. The reciprocating motion is converted to rotative motion by a barrel cam the output of which drives a tachometer-like instrument calibrated to show volume or weight of fuel used per unit of time. A lever operated bypass valve is associated with the meter to bypass the latter if desired. The meter is adjustable to compensate for expansion or contraction of the fluid or for different types of fuel. It is also within the concept of the invention to combine the rate meter hereof with other recording mechanism for making a permanent record of fuel usage. Furthermore, the meter may be combined with other treating means such as temperature control means and bubble removing means.

REFERENCE TO PRIOR APPLICATIONS

This is a division of application Ser. No. 214,913, now U.S. Pat. No.3,805,602 filed Jan. 3, 1972 for Fuel Use Rate Meter For Engines.

BACKGROUND OF THE INVENTION

This invention relates to a meter for measuring the rate of fluid flowsuch as for determining the rate of fuel usage in an engine.

The efficient functioning of engines comprises an important factor inthe operational aspect of trucking firms, marine firms, and other firmswhich use engine driven equipment. These engines are tested periodicallyfor output efficiency to determine whether or not repair or overhaul isnecessary. Various testing methods are used, a common one employing adynamometer. Another method to determine whether the engine is to berepaired or overhauled is merely by considering total miles run or hoursoperated. With the use of a dynamometer, or other methods now used, aprecise analysis of engine condition is not altogether possible becauseof variables which may exist from engine to engine such as ignitionconditions.

The most efficient method of determining engine condition is toascertain the amount of fuel consumed by the engine per unit of time.Prior devices, have not accomplished this method of testing in acommercially feasible manner because the meters used, while showing fuelusage, do not give a direct reading of the rate that the fuel is used.In prior devices, it is thus necessary to make computations from themeter reading, which of course is inconvenient and many timesinaccurate. Another disadvantage of prior devices is that they do notcompensate for the expansion or contraction of fuel due to variations intemperature, and thus the fuel is not accurately metered, particularlyin slow flow systems such as fuel feed systems for engines. Althoughtemperature conversion tables are available, based on a temperatureconstant, for determining volume of flow, such computing method is ofteninaccurate and always inconvenient. In some cases the use of conversiontables is also impractical.

In view of the above, means heretofore used for determining thecondition of engines by ascertaining fuel consumption or miles or hourslogged are not considered to be adequate because such means do notindicate with the necessary preciseness the condition of an engine. Thismay result in overhaul or repair which is not necessary, or on the otherhand engines may remain in operation when in fact they should beoverhauled or repaired.

SUMMARY OF THE INVENTION

It is therefore a primary objective of the present invention to providea meter for use in a fluid flow system which indicates directly the rateof fluid flow. Such a meter is particularly adapted for use inconjunction with a vehicle engine to show the rate at which fuel isbeing consumed and thus to indicate the mechanical condition of theengine.

Other objects of the present invention are to provide a meter of thetype described which includes adjustment means compensating fortemperature variations; which has a structure wherein indicating meansforming a part thereof may be remotely located from the drive means ofthe meter; which may be combined with other treating means such astemperature control means and bubble lever-operated bypass valve capableof either directing fuel through the meter or around the meter.

Additional objects will become apparent from the following descriptiontaken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a fuel system including the presentfuel use rate meter for engines;

FIG. 2 is a vertical sectional view of the present meter, taken on theline 2--2 of FIG. 3;

FIG. 3 is a horizontal sectional view taken on the line 3--3 of FIG. 2,this view being reduced in size relative to FIG. 2 and having some ofthe parts omitted;

FIG. 4 is an enlarged, horizontal sectional view taken on the line 4--4of FIG. 2;

FIG. 5 is an enlarged vertical fragmentary sectional view taken on theline 5--5 of FIG. 4;

FIG. 6 is a fragmentary vertical sectional view taken on the line 6--6of FIG. 2;

FIG. 7 is an elevational view of a barrel cam which comprises a part ofinternal drive means for the meter and which is shown apart from otherstructure for clarity;

FIG. 8 is a face view of an indicating instrument which forms a part ofthe present system;

FIG. 9 is a rear view of the instrument of FIG. 8 showing adjustmentmeans thereon;

FIGS. 10 through 14 comprise diagrammatic views of various fuel systemsincorporating the present rate meter;

FIG. 15 is a fragmentary plan view of an electrically operated pickupsystem between drive means of the meter and indicating means;

FIG. 16 is an elevational view, partly broken away, showing a modifiedform of rate meter;

FIG. 17 is a fragmentary bottom plan view on the line 17--17 of FIG. 16;

FIG. 18 is a fragmentary sectional view illustrating a modified form ofindicator drive means which may be associated with the structure of FIG.16; and

FIG. 19 is a fragmentary elevational view showing a modified structureof the barrel cam means of FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With particular reference to the diagrammatic view of FIG. 1, an engineis designated by the numeral 10 and conventional fuel feed meanstherefor comprising a fuel tank and a fuel line are designated by thenumerals 12 and 14, respectively.

Forming a part of the present invention is a fuel meter apparatus 16which upon being driven by fluid flow operates in a manner to provideaccurate information in a direct reading on an instrument to indicateoperating conditions of an engine, as will be more apparent hereinafter.

The meter 16 is structurally detailed in FIGS. 2 through 6. It comprisesan outer casing 18 of cylindrical shape. Casing 18 has a bottom wall 20with projections 21 thereon for a purpose to be described. A sleeve 22,forming a cylinder, is disposed within the casing 18. The casing has ahead 26 removably fitted therein.

As best shown in FIGS. 2 and 4, the casing 18 has an inlet 32 and anoutlet 34 disposed substantially in diametrical relation. The meterapparatus is associated with a bypass valve 35 to be describedhereinafter which preferably is formed with the casing 18 in a commoncasting. The housing for the meter and bypass valve is installed in thefuel line 14 by conventional means, with cut ends of the fuel lineengaging the bypass valve and outlet 34 in the casing 18 by suitablefittings 14a. A passageway 36 in the head 26 leads from the inlet 32 andopens into the interior of the meter casing, and a passageway 38 also inthe head leads from the outlet 34 and opens into the interior of themeter casing in laterally spaced relation to the outlet of the port 36.A third passageway 40 extends from a point of inlet interiorly of themeter casing which is disposed between the outlet of passageways 36 and38 to a side of the head beyond the sleeve 22, best seen in FIG. 4. Thehead 26 and the outer casing 18 are cut away vertically in the plane ofthe outer end of the port 40 to provide a vertical passageway 42, FIG.4. This recess establishes communication between the passageway 40 andthe bottom of the casing. It will thus be seen that the passageway 36leads from the inlet 32 to the top region of the casing, the passageway40 leads from the said top region to the bottom of the casing, and thepassageway 38 serves as an exhaust passageway connected to the meteroutlet.

Valve mechanism will now be described to cause the fluid to flowalternately to the upper and lower cylinder regions and ultimately beexhausted through the outlet 34 for driving plunger means up and down inthe cylinder. The head 26 has a depending, round center guide post 44projecting into the casing at about the center thereof. This postprojects integrally from the upper wall of a recess 45 cut in the lowersurface of head 26. Also depending from the head 26 but at the sides,are two guide posts 46 and 48 disposed in diametrically opposedrelation. Each of the posts 46 and 48 is formed with upper and lowerflanges 50 and 52 respectively, and a central horizontal projection 54on each side thereof, the flanges 50 and projection 54 being arranged toform horizontal slots between them which function as guides. Such guideslots are formed on two sides of the posts, namely, the front and rear,considering the front to be toward the viewer in FIG. 2.

The two posts 46 and 48 slidably support a valve support plate 56 on thefront side thereof, best seen in FIGS. 2 and 4. Valve plate 56 has apair of arms 58 on each end slidably received within the slots formed onthe front side of the respective posts 46 and 48, the valve plate andarms being of selected dimension as to be reciprocatable horizontally ashort distance within the casing. The posts similarly mount a loaderplate or slide 60 on the other or rear side thereof, this plate alsohaving spaced end arms 62, FIG. 5, received in a similar fashion in thepost slots as are arms 58 of valve plate 56 on the other side, theloader plate and its arms also being dimensioned so as to behorizontally reciprocatable a short distance. Washers 64, FIGS. 4 and 5,are provided at the front and rear of the support posts and are held inplace by bolts 66 to maintain the plates 56 and 60 within theirparticular slots of the posts. The loader plate 60 has two spaced arms68 which project substantially at right angles from the body of theplate in a forward direction and forward beyond the body of the valveplate 56 and below the latter. Attached to the portion of the valveplate 56 between the arms on the loader plate 60 is a trip element 70projecting both to the front and rear of the valve plate in parallelrelation to the arms 68. A shaft 72 is supported between the arms 68 andalso passes slidably through the trip element 70. A first compressionspring 76 is supported on the shaft 72 between the trip element 70 andone arm 68 of the loader plate and a second compression spring 78 issupported on the shaft 72 between the trip element and the other arm 68.

Valve plate 56 has a forwardly extending right angle tab or ear 80,FIGS. 2 and 6, disposed below the region of the outlets of the threepassageways 36, 38 and 40 into the casing, and mounted on such ear is aninverted cup valve 32 having a bottom stem 84 freely received within anopening provided therefor in the ear. A coil spring 86 is disposedbetween the ear and the cup valve about the stem and holds the valvefirmly against the underside of the head 26. As illustrated, the valvediameter is such that its hollow or recess portion bridges at one timeboth the outlets from passageways 36 and 40 or alternatively both theoutlets from passageways 38 and 40, depending upon the position of thevalve in two limit positions.

Slidably mounted on the post 44 is a piston rod 88. This rod has abox-like shape, FIG. 6, which provides for slidable connection on thepost, and projecting rearwardly from the piston rod at the upper endthereof is a drive pin or projection 90. Piston rod 88 has a lowertransversely extending cut-out portion 94, respectively, and post 44 hasa cut-out portion 96 which as will be more apparent hereinafter isadapted for lateral alignment with the cut-out portion 94 at a downposition of the piston rod. Drive pin 90 projects into an upright angledslot 98 in the loader plate 60, and upon up and down movement of thepiston rod, the loader plate is cammed first to one side and then to theother. Such movement of the loader plate in one direction compresses oneof the springs 76 between one of the arms 68 and the trip element 70 andin the other direction compresses the other spring between the other arm68 and the trip element 70.

Integrally connected to the bottom end of the piston rod 88 is a piston100, FIGS. 2 and 6, having a liquid tight positive seal engagement in asuitable manner at its peripheral edge with the inner wall of the sleeve22.

As to the operation of the meter, reference is first made to FIG. 2wherein the piston 96 is disposed at its lower position and the valve 82connects the passageway 36 with the passageway 40. Fluid at this time isdirected to the bottom of the casing through passageway 42 for liftingthe piston. As the piston is driven upwardly the fluid above the pistonin the casing is discharged through the outlet passageway 38. Alsoduring the upward travel of the piston, the loader plate 60 is caused tobe shifted to the right due to the camming action thereon by the drivepin 90, and this causes the spring 76 to be compressed since the valveplate 56 is restrained from moving correspondingly by engagement of itstrip element 70 with the left side of the piston rod 88 in the areaabove cut-out portion 94. Such upward travel of the piston continueswith progressive compression of the spring 76 until the bottom cut-outportion 94 of the piston rod reaches a height sufficient to allow thetrip element 70 to pass therethrough, such upper position of the pistonbeing shown in phantom lines in FIG. 2. This releases the valve platefor quick movement to the right under the action of the loaded spring76. Since the cup valve 82 moves with the valve plate 56 it will then bedisposed in a position connecting passageways 40 and 38. Fluid is thenintroduced to the upper area of the casing through inlet passageway 36and the piston is driven downwardly, the exhaust flow of the fluid atthe bottom of the piston being driven up through the vertical passageway42 and out the outlet passageway 38. As the piston moves downward, itcauses the loader plate 60 to be shifted to the left due to the cammingaction thereof from drive pin 90 and this causes the spring 78 to becompressed. Such downward travel of the piston continues until the tripelement 70 passes over the top of the piston rod 88. Movement of thetrip element 70 over the piston rod 88 allows the spring 78 to move thevalve plate 56 to its other position and again cause the fluid to bedirected under the piston. At this point the piston is slightly spacedabove the projections 21 of the bottom of the cylinder. The cycledescribed above is repeated continuously as long as fuel is supplied tothe meter.

Thus, as the piston reciprocates in its up and down movement, the loaderplate 60 reciprocates laterally. As a part of the present invention, itis desired that the output of the meter be rotational and the structureto be described and best shown in FIGS. 4, 5 and 7, is provided toconvert the lateral reciprocal motion of such loader plate to rotationalmovement for a purpose which will become more apparent hereinafter. Thedrive pin 90 on the piston rod 88 projects beyond the loader plate 60and is engaged in a sinuous type slot 102 in the periphery of an uprightbarrel cam 104 disposed adjacent to the rear side of loader plate 60.This cam has projecting shaft ends 106 for rotatable support in thecasing, the upper shaft end extending into a bearing socket 108 in thecasing and the lower shaft end rotatably engaged in a bore 110 in aU-shaped bracket 112 secured to the underside of head 26 as by screws113. The upper portion of the barrel cam 104 extends into a recess 114in the head 26 to accomplish proper operation of the drive pin 90 in thecam slot. The cam slot 102 is of selected positioning and shape suchthat as the piston moves up and down, the drive pin 90 rotates the cam.The particular shape of the cam slot allows the drive pin to move aroundthe ends thereof so that even though the pin is reversing direction inup and down movement, or vice versa, the cam rotates at a smoothuninterrupted speed. Cam 104 has surface projections 115 thereondisposed in spaced relation and having peak portions 115a. Engageablewith the projections 115 is one or more, preferably two in diametricalrelation, spring pressed ball assemblies 116 threadedly supported in thebracket. The spring pressed ball assemblies and projections 115 arearranged such that as the drive pin 90 is almost to an end or turnportion of the cam slot 102 the spring pressed ball thereof rides overthe ridge 115 to urge the barrel cam rotatably in its forward directionand insure that the drive pin will turn the corner and continue into thenext segment of the cam slot.

The upper end of barrel cam 102 integrally supports a drive gear 117having meshing engagement with a driven gear 118 secured on an outputshaft 119 rotatable in the head 26. Shaft 119 is secured to a coupling120 which connects this shaft to a flexible cable 122. Such coupling iscontained within a fitting 124 having a screw threaded mounting in thehead 26.

With reference again to FIG. 1, as well as to FIGS. 8 and 9, the cable122 leads to a tachometer-like instrument 132 having the usualindicating needle 134. This instrument is graduated in units 136 whichdepict fuel usage such as gallons or pounds. With proper calibration ofthe instrument 132 and lead angle of cam slot 102, an indication isavailable directly on the instrument of the fuel being consumed by anengine per unit of time to determine with the utmost accuracy the rateof fuel usage. Such reading can be used to determine the generalcondition of the engine under specific load conditions. Units 136 may begraduated for reading in volume of fluid per unit of time or volume offluid per unit of weight.

The tachometer-like instrument 132 includes counter means 138, FIG. 8,for permanently recording the volume of fluid used. This instrument mayalso have counter means 140 which similarly shows the volume used perunit of time or per unit of weight but which have reset means 142 forresetting the counter means 140 back to zero. Such an instrument, whichis of well known structure except for the graduated marking thereof,will thus indicate the rate of fuel usage and at the same time willrecord accummulated fuel usage and individual tests of fuel usage. Withreference to FIG. 9, which shows a rear view of the instrument 132,adjustment means 144 are available for adjusting the operation of theinstrument for a specific purpose or to correct the accuracy thereof.For example, the specific gravity of fuel may vary and it may benecessary to correct the accuracy of the instrument as related to theparticular specific gravity of the fuel.

The instrument 132 may be mounted closely to the meter 16 or since it isoperated by a flexible cable it may be mounted at a remote location. Thepresent fuel system has the advantage that the meter apparatus 16 may bemounted in the engine compartment and the instrument 132 mounted in thecab for easy viewing by the driver or by test personnel.

FIG. 10 shows a system somewhat similar to FIG. 1 with the exceptionthat a treatment tank 146 is provided in a line 148 extending from theengine 10 and connected into the fuel line 14 on the engine side of themeter apparatus 16. The system of FIG. 10 is used with an engine 10 ofthe type which returns unburned fuel, such as a Diesel engine. The tank146 has means 150 against which incoming fuel impinges for removing airbubbles from the return fuel if any. The tank is vented at 152 fordischarge of air. Tank 146 in addition to removing bubbles can be usedto cool the fuel in order that the fuel is fed back to the engine at aproper temperature.

FIG. 11 shows another system which includes a fuel tank 12, a fuel line14, the metering apparatus 16 in the fuel line 14, and an engine, notshown, together with a return line 148 as in FIG. 10. Line 148 may havea treatment tank, not shown, similar to tank 146 in FIG. 10, if desired.The system of FIG. 11 differs from FIG. 10, however, in that the fuelreturn line 148 from the engine is connected back into the fuel tankinstead of into the fuel line 14 and such return line includes a secondfuel meter 16a adapted to record the flow of fuel similar to the meter16. Since unburned fuel is returned to the tank 12, the exact amount offuel consumed by the engine will comprise the differential of readingsbetween meters 16 and 16a. For this purpose, the outputs from the twometers 16 and 16a are fed to a proportioning gear box 153 the output ofwhich is fed to the tachometer-like instrument 132 by a flexible cable154. The indication on instrument 132 will thus give the rate of fuelconsumption by the engine.

FIG. 12 shows still another system which is similar to FIG. 10,employing a fuel tank 12 and a fuel line 14 leading between the tank andthe engine 10. The system also employs a return line 148 having atreatment tank 146 therein. The system of FIG. 12, however, includestemperature control means 155, which serves to admit fuel to the engineat a constant temperature. Such unit has suitable cooling meanscontrolled by a thermistor 156. In the system of FIG. 12, great accuracyof engine performance is determined from instrument 132 since the fuelis fed to the engine at the most desirable conditions.

FIG. 13 illustrates an arrangement wherein the fuel meter 16 drives acable 122 as in previous embodiments but instead of the cable 122driving the instrument 132 directly said cable leads to a gear box 158having a dual output 122a and 122b in direct ratio drive. The output122a leads to the tachometer-like instrument 132 and the output 122bleads to a recording mechanism 160. The recording mechanism is ofconventional construction, comprising the usual clock driven circularchart on which is recorded by means of a stylus the rotative operationof output 122b. By means of this system, not only can personneldetermine the volume of fuel being used per unit of time or per unit ofweight but in addition a permanent record is made of the fuel used perunit of time or per unit of weight.

FIG. 14 shows a further extension yet of a concept of the invention. Itspurpose is to combine the output of a meter of the type described whichmeasures fuel usage per unit of time with the output of a speedometer toget a resultant reading of fuel usage of distance or revolutions pergallon. For example, the output cable 122 from the meter 16 operates asensor 170 and an output cable 172 from a speedometer 174 which isdriven by the drive shaft of the vehicle or, if used to designate boatengine operation, by the propeller shaft, operates a sensor 176. Theoutput from sensors 170 and 176 are combined electrically in a voltageor pulse divider 178 to get a resultant force on an electricallyoperated meter 180 depicting fuel usage per unit of distance. That is,by feeding gallons per hour, for example, into sensor 170 from meter 16and feeding miles per hour into sensor 176 from speedometer 174, theresulting output from voltage divider 178 will designate miles pergallon, or if for boat operation, knots per gallon. Meter 180 has anoutput for driving a recording mechanism 160 of a type previouslydescribed.

FIG. 15 shows a concept of the invention wherein a tachometer-likeinstrument 132' comprises an electrically operated tachometer of wellknown structure. For this purpose, the output shaft 119 supports anddrives a gear 182 at the upper surface of head 26. Mounted on the head26 is an electro-magnetic pickup device 184 of well known structureconnected electrically to the tachometer-like instrument 132'. Rotationof the output shaft 119 is thus transferred electrically to theinstrument 132' and as in other structures herein the instrument recordsdirectly the rate of fuel consumption.

Referring particularly to FIGS. 2 and 3, the bypass valve 35 is cast asan integral part of meter 16. It has a hollow interior including a bore190 and upper and lower chambers 192 and 194, respectively, on oppositeends of the bore. Inlet 32 to the meter leads from upper chamber 192 ofthe valve. Forming the operative part of the valve is a stem 196 ofconsiderably less diameter than the bore 190 and movable axiallytherein. Secured to upper and lower ends of the stem are diaphragms 198and 200, respectively, abutting against shoulder portions 202 in thehousing. The chambers 192 and 194 are closed at the ends by removablewalls 204 and 206, respectively.

The diaphragms 198 and 200 have tapered hubs 208 and 210, respectively,engageable with the end edges of the bore 190 to control the flow offuel through the valve. The arrangement of the parts is such that thestem 196 and the hubs 208 and 210 are movable axially a short distance,and the hubs in such axial movement are arranged to have wedging sealingabutment against one or the other of the respective end edges of thebore 190.

The valve housing has an outlet passageway 214 which extends up fromchamber 194 to one side and out of communication with bore 190, and thispassageway communicates with a passageway 216 extending around the valvehousing and meter casing, FIG. 3, to the outlet 34 of the meter casing.An inlet passageway 218 extends from an outer side of the valve housingbetween bore 190 and fuel line 14.

In the operation of the valve, flow from the inlet passageway 218 andbore 190 can flow through either the inlet 32 to the meter and outoutlet 34 or through outlet 214 to bypass passageway 216 and out outlet34, depending upon the position of stem 106. That is, in a down positionof the stem as shown, fuel from fuel line 14 bypasses the meter byflowing through the latter route mentioned above, namely, throughpassageway 218, bore 190, passageway 214, bypass passageway 216 andoutlet 34 to the fuel line 14. In the up position of the stem, fuel fromfuel line 14 flows through the meter 16, namely, through passageway 218,bore 190, passageway 32 and passageway 36.

The stem 196 is urged to an upper position by a compression spring 220between end wall 206 and the stem wherein normal flow is through themeter. However, to position the stem to a down position, a lever 222 ismounted pivotally between a pair of ears 224 on top of the valvehousing, and this lever has a cam end 226 in engagement with a verticalpin 228 extending slidably through the top wall 204 and abutting againstthe top end of stem 196. In normal metering flow, the lever 222 is thuspositioned so as to allow the spring 220 to raise the stem. If it shouldbe desirable that the fuel flow bypass the meter, the lever ispositioned so as to lower the stem to the position shown in FIG. 2.

FIG. 16 shows a somewhat modified form of meter 16'. This meter, similarto the meter shown in FIG. 206, has an outer casing 18', a piston 100'and mechanism for operating the plunger up and down in reciprocatingmotion which includes the piston rod 88 and the other structure whichwill not be repeated for this embodiment, including the fluid passagewaymeans and valve means for causing the reciprocating drive movement ofthe plunger.

In the structure of FIG. 16, the piston or plunger 100' comprises a nut234 secured integrally to the bottom end of piston rod, and this nutthreadedly receives a shaft 236 which extends through the bottom wall ofthe casing in a fluid seal 237. The shaft also extends through thepiston 100' and a pair of plates 238 disposed on opposite faces of thepiston. These plates have arcuate or bulbular portions 240 and areconstructed of metal having a high coefficient of expansion, wherebyupon variation in temperature the arcuate portions expand away from andcontract toward the piston. The piston carries an outer gasket 242 toprovide sealing engagement with the inside surface of the casing, andthe outer peripheral edges of the plates 238 extend between a flangeportion 244 of the gasket and the piston. The diameter of the plates 238is slightly less than the diameter of the piston to allow for lateraladjustment of the peripheral edge of the plates upon expansion andcontraction.

Threadedly mounted on the shaft 236 on the bottom side of the piston andon the outside of the bottom plate 238 is a nut 246. The two threadedportions of the shaft 236 which engage the respective nuts 234 and 246have opposing thread in an arrangement such that when the shaft 236 isturned in one direction the nuts draw the plates inwardly toward eachother and upon rotation of the shaft 236 in the opposite direction thebulbular portions of the plates are moved apart. Compression springs 243maintain the bulbular portions of the plates outwardly against therespective adjusting nuts.

The projecting end of shaft 236 carries a knob 250 which as best seen inFIG. 17 is associated with graduation marks 252 provided on the bottomof the casing 18'. Such graduation marks indicate adjusted rotativepositions of the shaft 236 in the positioning of the bulbular portions240 of the plates 238 relative to the piston 100' for a purpose to bedescribed hereinafter.

As was described hereinbefore in connection with the structure of FIGS.2-5, the piston is operated by fluid in a reciprocating motion fordriving indicating or counter means. In such reciprocating action, itdrives a selected amount of fluid from areas on each side thereof. Thestructure of FIG. 16 automatically adjusts itself to meter accuratelyeven though the volume of the fluid therein changes due to a variationin temperature. That is, the plates 238 have specific expansion andcontraction characteristics such that when the fuel is warmer than a setconstant, they expand away from the piston 100 to reduce the volume ofthe area in which the stroke of the piston occurs. By correlating theexpansion characteristics of the plates 238 and the expansioncharacteristics of the fluid, exact metering is accomplished. If theliquid should cool below the constant, the plates 238 contract toenlarge the areas in which the piston operates. The expansioncharacteristics of fluids of different specific gravities may vary, andfor this purpose the shaft 236 may be rotatably adjusted by knob 250 toposition the plates 238 according to well known characteristics ofexpansion and contraction of various liquids. A proper setting of theknob 250 as determined by the specific gravity of the fuel being meteredwill provide accurate results.

In the embodiment of FIG. 16, the head 26' of the meter is alteredrelative to the structure of FIG. 1 to the extent that it contains acounter mechanism 256 of conventional construction operating on a shaft258. One end of the shaft has a bevel gear 260 secured thereon andaccording to the present invention, the output shaft 119 instead ofprojecting through the head as in FIG. 5, has a bevel gear 262 thereonin mesh with the bevel gear 260 for driving the counter mechanism 256.The head 26' has a removable cover 264 with a transparent or windowportion 266 for viewing the counter.

FIG. 18 is a fragmentary section view of a portion of the head 26' andshows an embodiment wherein an end of shaft 258' of the countermechanism 256 has a coupling 268 with a flexible shaft assembly 270which leads to a remote counter system or a tachometer-like instrument132 of the type previously described. By means of the structures of FIG.18 remote counter means may be made available in addition to the counter256 so that even though the meter is mounted in the motor well of avehicle, the counter can be located in the cab.

FIG. 19 shows a modified structure of the barrel cam 104'. The cam ofthis embodiment, while having the same slot structure and operation asdescribed in connection with FIG. 7, employs leaf springs 274 at theends of the cam slot 102. These springs are positioned to one side ofthe slot end, such positioning being on the side in which the drive pinis advancing. They are arranged such that when the pin has passed thespring, it is advanced around the turn and cannot travel back in thesame segment of the slot. As the pin springs past springs 274, the camis also urged forwardly so as to rotate smoothly and withoutinterruption when the drive pin is at the turn.

SUMMARY

According to the present invention, a fuel system is provided whichallows operators to not only operate an engine in the most efficientmanner but also to examine fuel usage to test the condition of theengine. That is, by viewing on the instrument 132 the volume of fuelbeing used per unit of time or per unit of weight under a particularload condition, a most efficient method is available of directlyascertaining engine efficiency and consequently whether or not theengine needs repair or overhaul. Such method has important advantagesover other types of engine tests because an accurate knowledge of fuelconsumption based on a particular load gives a direct indication withoutvariables of the engine's condition.

The system of FIG. 12 is even more accurate in that the fuel is alwaysfed to the engine at optimum conditions for greater efficiency. Thestructure of FIG. 16 wherein adjustment is made for the temperature ofthe fuel provides for even greater efficiency, and it is to beunderstood that such type of meter can be used with any of the systemsdisclosed herein. Adjustment of the expansion means in the meter of FIG.16 according to the specific gravity of the fuel is accomplished byadjusting knob 250. In connection with the embodiment of FIG. 16, theoutput shaft 258' can drive a flexible cable assembly 122 as in theembodiment of FIGS. 2-5 wherein the meter casing 18' can be placed inthe motor well and the indicator or counter means driven thereby can beplaced in the cab or other place which is convenient for inspection.

The present system may be used in conjunction with almost any engine ofthe fuel burning type such automotive, marine or stationary engines. Thethrottle of an engine may be set by use of the present rate meter ratherthan by revolutions per minute.

It is to be understood that the forms of my invention herein shown anddescribed are to be taken as perferred examples of the same and thatvarious changes in the shape, size and arrangement of parts may beresorted to without departing from the spirit of my invention or thescope of the subjoined claims.

Having thus described my invention, I claim:
 1. A fluid fuel system incombination with an engine comprising a fuel tank, a fuel line extendingfrom said tank to the engine, said engine being of the type in which aportion of the fuel fed thereto is unburned, a return line from saidengine leading back to said fuel tank, a positive seal, positivedisplacement meter connected into the fuel line for measuring fuel fedto the engine, said meter having a driven output operative continuouslyas long as fuel is flowing through the meter, a positive seal, positivedisplacement meter connected into said return line and also having adriven output operative continuously as long as fuel is flowing throughthe latter meter, indicating means calibrated to show fluid flow,proportioning means receiving the outputs from said two meters, saidproportioning means having an output comprising the differential inoutput of said two meters, and means connecting the output of saidproportioning means to said indicating means whereby the latterindicates a continuous and direct reading of the fuel being consumed bysaid engine.
 2. The fluid fuel system of claim 1 wherein said indicatingmeans indicates a continuous and direct reading of the rate of fuelbeing consumed by said engine.
 3. The structure of claim 1 wherein saidindicating means indicates a continuous and direct reading of the rateof fuel being consumed by said engine and further indicates a totalamount of fuel consumed.
 4. The structure of claim 1 wherein saidindicating means also indicates total number of movements generated pertotal quantity of fuel consumed.
 5. The structure of claim 1 includingrecording means driven by the output of said proportioning means.
 6. Thestructure of claim 1 including temperature control means in said fuelsystem.
 7. The structure of claim 1 wherein said indicating means iscalibrated to indicate a direct reading of the rate of fuel beingconsumed by said engine in revolutions per unit of fuel.
 8. Thestructure of claim 1 wherein said indicating means is calibrated toindicate a direct reading of the rate of fuel being consumed by saidengine in units of weight per unit of time.
 9. The structure of claim 1wherein said indicating means is calibrated to indicate a direct readingof the rate of fuel being consumed by said engine in units of fuel perunit of time.
 10. The structure of claim 1 wherein said indicating meansis calibrated to indicate a direct reading of the rate of fuel beingconsumed by said engine in units of time per unit of fuel.
 11. A fluidfuel system arranged for use with an engine having fuel feed means, apositive seal, positive displacement fluid flow meter operated by theengine fuel feed means, indicating means driven by said meter comprisinga direct reading of the rate of fuel being consumed by the engine, andtemperature control means arranged for use with the fuel system tocontrol the temperature of fuel therein.
 12. A fluid fuel system incombination with an engine, fuel feed means for said engine, said enginebeing of the type in which a portion of the fuel thereto is unburned, areturn line from said engine leading back to said fuel feed means toreturn the unburned fuel, a positive seal, positive displacement fluidflow meter operated by said engine fuel feed means, and indicating meansdriven by said meter comprising a direct reading of the rate of fuelbeing consumed by said engine.
 13. The structure of claim 12 whereinsaid indicating means also is calibrated to indicate the total amount offuel consumed.
 14. The structure of claim 12 wherein said indicatingmeans is calibrated to indicate a direct reading of the rate of fuelbeing consumed by said engine in revolutions per unit of fuel.
 15. Thestructure of claim 12 wherein said indicating means is calibrated toindicate a direct reading of the rate of fuel being consumed by saidengine in units of weight per unit of time.
 16. The structure of claim12 wherein said indicating means is calibrated to indicate a directreading of the rate of fuel being consumed by said engine in units offuel per unit of time.
 17. The structure of claim 12 wherein saidindicating means is calibrated to indicate a direct reading of the rateof fuel being consumed by said engine in units of time per unit of fuel.18. The structure of claim 12 including recording means driven by saidindicating means.
 19. The structure of claim 12 including temperaturecontrol means in said fuel system.
 20. The structure of claim 12including by-pass means in combination with said flow meter, andshiftable means in said by-pass means arranged to direct fluid into saidmeter or to by-pass said meter.
 21. A fluid flow system in combinationwith an engine, fuel feed means for said engine, said engine being ofthe type in which a portion of the fuel fed thereto is unburned, areturn line from said engine leading back to said fuel feed means toreturn the unburned fuel, a treatment tank in said return line, a fluidflow meter operated by said fuel feed means, and indicating means drivenby said meter comprising a direct reading of the rate of fuel beingconsumed by said engine.
 22. The structure of claim 21 wherein saidindicating means also is calibrated to indicate the total amount of fuelconsumed.
 23. The structure of claim 21 wherein said indicating means iscalibrated to indicate a direct reading of the rate of fuel beingconsumed by said engine in revolutions per unit of fuel.
 24. Thestructure of claim 21 wherein said indicating means is calibrated toindicate a direct reading of the rate of fuel being consumed by saidengine in units of weight per unit of time.
 25. The structure of claim21 wherein said indicating means is calibrated to indicate a directreading of the rate of fuel being consumed by said engine in units offuel per unit of time.
 26. The structure of claim 21 wherein saidindicating means is calibrated to indicate a direct reading of the rateof fuel being consumed by said engine in units of time per unit of fuel.27. The structure of claim 21 including recording means driven by saidindicating means.
 28. The structure of claim 21 including temperaturecontrol means in said fuel system.
 29. The structure of claim 21including by-pass means in combination with said flow meter, andshiftable means in said by-pass means arranged to direct fluid into saidmeter or to by-pass said meter.